Pub/Sub RESP replies
In Redis Pub/Sub, the messaging format is in RESP Array reply with three or four elements. The first element in the Pub/Sub messaging format determines the type of message and can be one of these four Redis commands, SUBSCRIBE
, UNSCRIBE
, PSUBSCRIBE
, and PUNSUBSCRIBE
.
SUBSCRIBE and UNSUBSCRIBE RESP Arrays
Connecting to a Redis instance with two connections, the first with a standard Redis CLI client and the second with telnet, we will illustrate the RESP reply for three element commands SUBSCRIBE
and UNSUBSCRIBE
:
$ telnet localhost 6379 Trying ::1... Connected to localhost. Escape character is '^]'. SUBSCRIBE info *3 $9 subscribe $4 info :1
In this SUBSCRIBE
command, the first element is $9
followed by carriage-return line feed. The second element is the channel, info, that the client is subscribing to, with the third element in a subscribe message being the number of channels that the client is currently subscribed to receive messages. In our Redis CLI, we'll send a message...